Hydrocarbon synthesis with fluidized catalyst regeneration



E. A. JOHNSON HYDROCARBON SYNTHESIS WITH FLUIDIZED Aug. 24, 1948.

CATALYST REGENERATION Filed April 13, 1944 v 2 Sheets-Sheet 1 Q MM mw MM Aug. 24, 1948. E. A. JOHNSON 2,447,595

' HYDROCARBON SYNTHESIS WITH FLUIDIZED CATALYST REGENERATIQN 2Sheets-Sheet 2 Filed April 13, 1944 fnvenfor- Eve/"eff ,4. Johnson 3WMZMMQ fed 623 l Patented Aug. 24, 1948 HY DROCARBON SYNTHESIS WITHFLUID- IZED CATALYST REGENERATION Everett A. Johnson, Park Ridge, 111.,assignor to Standard Oil Company tion of Indiana Chicago, Ill., acorpora- Application April 13, 1944, Serial No. 530,875

This invention relates to hydrocarbon synthesis with fluidized catalystregeneration and it pertalns more particularly to improved methods andmeans for the continuous regeneration of cobalttype catalysts and fOrutilizin regeneration gases in a carbon monoxide-hydrogen synthesissystem for producing hydrocarbons having more than one carbon atom permolecule. With respect to general catalyst handling methods, this appcation is a continuatlon-in-part of my copendlng applications includingSerial Nos. 392,846--7 filed May 10, 1941, and Serial 30, 1942.

In the synthesis of hydrocarbons from carbon' .15 lysts, the catalystparticles gradually lose their monoxide and hydrogen with cobalt-typecataactivity, partly at least On account of the deposition of excessiveamounts of wax and wax-like materials thereon. It has been necessary insuch processes to periodically discontinue the synthesis reaction andto-regenerate the catalyst by contact with hydrogen. gradually declines,between regeneration steps and a variable load is thus imposed upon theproduct fractionation and recovery systems'be-. cause of the change inproduct distribution and product yieldswhich inevitably takes place whenthe catalyst loses activity. An object of my invention is to provide amethod and means whereby the catalyst remains at substantially constantactivity sothat product distribution and yields remain substantiallyconstant, the load on the fractionation system remains substantiallyconstant and shut-down periods are avoided with the consequent savingsin operating expense and increases in overall capacity.

A further object of the invention is to produce a. greater conversionwith a given amount of cata lyst than has heretofore been possible. Afurther object is to utilize hydrogen in the regeneration No. 428,913filed January" The catalyst activity 1Clalm. (Cl. 260-4493) erationzone. I continuously transfer catalyst from the liquid-like denseturbulent suspended catalyst phase in the synthesis zone tothe rgeneration zone and continuously transfer regenerated catalyst from theliquid-like dense turbulent suspended catalyst phase in the regenerationzone back to the synthesis zone. The charge gas to the synthesis zone isa hydrogen-carbon monoxide mixture in an approximately 221 mol ratio.

The regeneration gas is essentially hydrogen and although it may containmore or less inert diluents, its CO content should be so low as iscommercially feasible. The hydrogen is usually not utilized to themaximum extent in a oncethrough operation and I may therefore recycle asubstantialamount of the gases leaving the regenerator with the hydrogenwhich is introduced thereto. The hydrogen-rich gases from theregeneration step may also or alternatively be used for aeration and/ortransfer of catalyst in the substantial absence of carbon monoxide. The.useof such gas for carrying catalyst through a cooler is particularlyadvantageous because it efiects at least partial stripping andregeneration thereofv while-the catalyst is passing through the coolincircuit. Certain advantages of the invention are attainable, however,even though the gases from the regeneration zone are introduced into thesynthesis zone, the effluent product stream or absorber. When gases fromthe regeneration zone are mixed with feed gases entering the synthesiszone, such feed gas may be deficient in hydrogen and the deficiency maybe supplied step more effectively than it has been utilized in any priorregeneration operations and to minimize the production of methane and toincrease the production of valuable liquid hydrocarbons obtainable inthe regeneration step as well as in the synthesis step itself. A furtherobject is to use regeneration gases from the regeneration step moreeiiectively and for difi'erentpurposes than by the hydrogen-richregeneration gases.

It is essential that the regeneration be effected in a zone which isseparate and distinct from the conversion zone because any substantialincrease in hydrogen in the conversion zone'and in the presence ofcarbon monoxide leads to excessive methane production and greatlydecreases the yields of liquid products. However, the regeneration zoneand synthesis zone may be in one and the same chamber provided thatsuitable 'bafiles 0r seals are provided to maintain the zones separateand distinct. A feature of my invention is the provision of seals whichdepend for'their operation on the relative densities of the fluidizedcatalyst solids in different'parts of the system.

By varying the amount of aeration gas which is.

' generation zones.

The fluidized mass of catalyst thus may serve effectively as the sealbetween reaction and re- Such seals may likewise be employed to preventback-flow through cyclone separator dip legs. Other features of theinvention will be apparent from the following detailed description ofspecific examples thereof read in conjunction with the accompanyingdrawings which form a part of this specification and in which Figure 1is a. schematic flow diagram of my conversion-regeneration systememploying external catalyst regeneration;

Figure 2 is a schematic flow diagram of such a system employing internalreg neration;

Figure 3 illustrates a modified form of the internal regenerationsystem;

Figure 4 illustrates a modified form of the external regenerationsystem, and

Figure 5 is a detailed vertical section taken across a cyclone separatordip leg and its associated elements.

The feed gas for the synthesis reaction when using a cobalt-typecatalyst is a mixture of hydrogen and carbon monoxide in approximately a2:1 ratio and it may be obtained from any source known to the art. Itmay be prepared by reacting natural gas (methane) with carbon dioxideand steam noncatalytically at temperatures upward of 2000 F. or in thepresence of catalyst.

such as nickel supported on alumina or firebrick at a temperature ofabout 1400 to 1800 F., usually within the approximate range of 1500 to1600 F. at substantially atmospheric or slightly superatmosphericpressure. The feed gas, however, may be obtained from any source such ascoal, shale or other carbonaceous material in manners which are wellknown to the art and which require no detailed description. The feed gasshould be substantially free from sulfur, i. e. should contain less thanabout .1 grain of sulfur per 100 cubic feet of gas (all gas volumes:being thus measured at atmospheric pressure and 60 F. temperature).Small amounts of nitrogen and carbon dioxide may be tolerated but it isdesirable to keep such inert diluents to a minimum.

The catalyst for the synthesis step is preferably of the cobalt type. Itpromotes the reaction The catalyst should be in finely divided form, i.e. should substantially all pass a 30 or 40 mesh screen and should haveparticle sizes chiefly within the range of 2 to 200 microns orpreferably about 20 to 100 microns. In other words, the

. catalyst should be in such finely divided or powdered form that it canbe "fluidized by gases upwardly therethrough at low velocity andmaintained in dense phase turbulent suspension without segregation,slugging or other diificulties which result from the use of largecatalyst particles or high gas velocities. The optimum gas velocity isWithin the approximate range of 1 to 3 feet per second, e. g. about 1foot per second although for some catalysts the gas velocity may be aslow as .4 and in other cases it may be as high as 4 feet per second. Theuse of catalyst particles of such structure, shape and size as to befluidized by upfiowing gases of such velocity is an important feature ofthe invention.

The cobalt type catalyst may consist essentially of supported cobalteither with or without one or more promoters such as oxides of mag- Ybait support is preferably an acid treated behtonite or montmorilloniteclay such as Super Filtrol, but it may .be diatomaceous earth orkieselguhr, especially a kieselguhr of low calcium and iron content. Aporous structure is of course essential and most clays requirepretreatment by ignition and acid washing. Other supports such askaolin, alumina, silica, magnesia and the like may be employed but aSuper Filtrol support is preferred. The catalyst may be prepared bypre-- cipitating cobalt and promoter carbonates from nitrate solutionsin the presence of the support. In the case of thoria, for example, thepromoter may be in amounts of 1-5 or 20% based on cobalt, higher thoriaconcentrations being objectionable because of their tendency to promotewax formation. The cobalt-Super Filtrol ratio may be varied from about5:1 to .121 but is usually about 0.321 to 1:1. The precipitated catalystafter filtering, washing and drying is reduced before use, preferablywith hydrogen, at a temperature of about 400 to 650 F. A typicalcatalyst ready for use may contain about 32% cobalt, 1/z% thorium oxide,2 /g% magnesium oxide and 64% Super Filtrol. No invention is claimed inany specific catalyst composition or in any method of making thecatalyst and since such compositions and methods are well known to theart they will require no further description.

The invention is not limited to catalysts in which cobalt is theessential component but is applicable to such catalysts as nickelcatalysts, ruthenium catalysts and in fact any and all catalysts whichare regeneratable by hydrogen under approximately the temperature andpressure conditions of the synthesis step.

A commercial plant for producing 5000 barrels per day of hydrocarbonsynthesis product liquid (including butanes) with a cobalttype catalystwill require a reactor about 30 to 35 feet in diameter and about 60 to70 feet in height when operating at about 45 pounds per square inchgauge at a temperature of about 400 F. Operations effected at lowerpressure will require reactors of increased diameter or a plurality ofreactors while operations at higher pressure will require lesserdiameters but increased height. Usually the reactor for any operatingconditions is designed for an .upflow gas or vapor velocity ofapproximately 1 feet per second. From these general principles and thedetailed description of a specific commercial unit reactor, sizes andshapes may readily be computed for other catalysts and operatingconditions.

Referring to Figure 1, the feed gas stream is introduced from source Itthrough line H to reactor 12 and it is preferably distributed at thebase of the reactor by a perforated plate or other distributor means i3.The reactor in this case is a cylindrical vessel about 30 feet indiameter by about 70 feet in height. The feed gas consists essentiallyof hydrogen and carbon monoxide in approximately a 2:1 ratio and thefeed rate is in the general vicinity of 6,000,000 cubic feet per hour.The gas is introduced at about 3 atmospheres or about 45 pounds persquare inch gauge.

The reactor I 2 contains in the general vicinity of 1 to 4, e. g. about2 to 2 million pounds of the finely divided cobalt-type catalyst. Withan upward linear velocity of about 1 /2 feet per second 'in the reactorthis catalyst is maintained in suspended turbulent dense phase conditionat a density in the general vicinity of 40 to 60 pounds per cubic foot,the densities depending of course upon the particular type of catalystbut it should be about .3 to .9, preferably about .5 to .6 times thedensity of the settled catalyst. The space velocity through the reactormay be in the general vicinity of 50 to 500 or more volumes of gas perhour per volume of space occupied by the dense catalyst phase and isusually within the range of about 100 to 200, or about 150 cubic feetper hour per volume of reactor occupied by dense phase catalyst, all gasvolumes being measured at 60 F. and atmospheric pressure.

The heat of reaction may be dissipated and the reaction temperature maybe held at the desired level of between about 300 and 425 F. byrecycling catalyst through an outsidecooler, a will be hereinafterdescribed, or cooling coils or tubes can be provided within thesynthesis reactor l2. Alternatively water condensed and separated fromthe product stream may be returned and sprayed or atomized into thereactor itself .at the rate of approximately 20,000 to 35,000 gallonsper hour. A fraction of the product stream boiling chiefly within therange of about 250 to about 350 F. may likewise be recycled, sprayed oratomized into the reactor at various levels. The use of the outsidecooler offers particular advantages in my system in that it provideseifective means forvutilizing hydrogen-rich gas mixtures and foraugmenting the removal of waxy deposits from catalyst surfaces.

The bulk of the catalyst separates from the light dispersed phase whichis maintained above the dense phase in the. reactor and settles back tosaid dense phase. Residual amounts of entrained catalyst particles maybe separated from the exit gas stream by means of one or morecentrifugal separators of the cyclone or multiclone type and suchseparators may be employed in any required number and mounted either inparallel or series, or both. Such centrifugal separation means isdiagrammatically illustrated in the drawing by cyclone separator Mprovided with inlet I5, dip leg l6 and gas outlet IT. The clip legextends vertically downwardly into the dense catalyst phase andit ispreferably surrounded at its lower end by a tube I8 (note Figure 5)having a closed bottom end I9 through which an-aeration gas isintroduced through line and directed toward the annular space betweendip leg l6 and tube 13 by means of a distributor 2|. This distributormay be a cone-shaped element welded to bottom wall l9 so that the uppersurface of the cone-shaped element may serve to deflect catalyst towardthe outer annular space and the aeration gas may supplement and expeditethe dispersion of the catalyst in this annular space and maintain thecatalyst in the annular space in more highly aerated condition than thecatalyst which is flowing downwardly in dip leg IS. The tube or boot l8thus provides a seal for the lower end of dip leg I6. that any pressuresurges in the reactor will not be transferred to dip leg IS. The lowerdensity of the catalyst in the annular space and the gas lift effect ofthe aeration gas insures smooth and uninterrupted flow from the base ofthe dip leg into the reactor and thus prevents any blow-back or cloggingof the dip leg. Bottom wall I9 prevent-s upflowing gases in reactor l2from entering dip leg IS. The use of a column of catalyst in the dip legfor counterbalancing the pressure drop through the cyclone separator ismore fully described in U. S. Letter Paten-t 2,337,684.

The overhead stream from the top of the reactor, or from line I! ifcyclone separator are employed, passes through line 22 and cooler 23through line 380.

to separator 2! from which water may be withdrawn through line 25,liquid hydrocarbons through line 26 and gases and vapors through line27. The gases and vapors are passed by compressor 28 to absorption:tower 29 wherein it countercurrently contacts absorber oil introducedthrough line 30, the unabsorbed gases removed through line 3| beingrecycled to the reactor, employed for producing synthesis gas, or burnedas fuel. Rich absorber oil passes through line 32 and heat exchanger 33to stripping settler 34 which is provided with a suitable heater 34a.Lean absorber oil from the base of the stripper is returned through line35, heat exchanger 33 and cooler 33a to absorber tower 29.

line 36 to fractionating system 31 from which a normally gaseoushydrocarbon stream may be withdrawn through line 38, a gasoline boilingrange stream through line 38a, a ga oil boiling range stream through381) and a residual stream The fractionation system is diagrammaticallyillustrated in the drawlugs and in actual practice it will of course beunderstood that it will include a plurality of columns, suitablereboiling and reflux mean 'associated with each column, etc. but sincesuch'fracti-onationsystem-s are well known to those skilled in the artthey will require no detailed description. In accordance with myinvention the load on the absorption and fractionation system remainssubstantially constant because of the uniform activity of the catalystin the reactor which is maintained in the manner which will now bedescribed.

Extending upwardly in reactor l2 to a point below the upper level of thedense catalyst phase is a conduit 39 which forms the upper part of thestandpipe 40. The dense phase cataylst which accumulates in thisst-andpipe is maintained in aerated condition by the introductionofvanaeration gas such as hydrogen, steam, carbon dioxide or the likethrough line ll Catalyst is discharged from the base of this standpipein amounts controlled by valve 42 into transfer line 43 into whichhydrogen is introduced through line M and a hydrogen-rich recycle gasmay be introduced through line t5. Catalyst thus suspended in the lentsuspended phase of catalyst material in the lower part of theregenerator superimposed by a light dispersed catalyst phase and whilethe velocities may be of the order of 1 to 3 feet per second they arepreferably of the order of .2 to 2 feet per second. Most of the catalystsettles by gravity from the dispersed phase to the dense phase but hereagain centrifugal separator may be employed for knocking back anyentrained catalyst particles. Such separators are diagrammaticallyillustrated by cyclone separator 41 provided with inlet 48, dip leg 49and discharge line 50. The lower end of the dip leg may be surrounded bya suitable boot at the base thereof into which an aeration gas may beintroduced in the manner more specifically illustrated in connectionwith Figure 5.

Catalyst is removed from regenerator 46 at substantially the same rateas it is introduced thereto and its,average holding time in theregenerator may be within the approximate range of about 1 minuteto anhour or more, for example, about minutes. Catalyst is removed from theregenerator through conduit 53 which forms the upper part of standpipe aThis standpipe may likewise be provided with a line I for introducing anaeration gas at its base and with a valve .58 for controlling the rateat which catalyst is introduced into line H wherein it is picked up withincoming feed gas and returned to reactor l2. It should be understoodthat while only a single aeration gas line is shown on standpipes and 5%a plurality of such aeration means may be employed.

I In this particular example the reactor is operated at about pounds persquare inch gauge pressure and at a temperature of about 400 F. but itshould be understood that the temperature may be within the approximaterange of 300 to 450 F. and the pressure may be from substantiallyatmospheric pressure to 100 pounds per square inch or higher. Thepressure in the regenerator should be approximately the same as that inthe reactor. Standpipe 40 should be of such height as to provide apressure at its base which is slightly higher than the pressure in linecatalyst, such removal being particularly important in fluidizedcatalyst operations.

- The gases leaving the upper part of the regenerator 45 through line 51are usually still quite rich in hydrogen. These gases may be combinedwith feed gases entering the reactor through line H, in whichcase anyhydrogen deficiencies in the feed gases may be made up by the hydrogenin the regeneration gases so that the gas mixture entering the reactorwill contain hydrogen and carbon monoxide in the desired ratio.Regeneration gases from line 51 may also be combined with the emuentproduct stream in line I 22 or they may be compressed and introduced l3and standpipe 54 should be of such height as to provide a pressure atits base which is slightly higher than that in line H; the standpipesthus provide the necessary pressure for catalyst transfer and act asseals to prevent backiiow of gases. The energy required for circulatingcatalyst is supplied'by the gas streams entering the reactor and theregenerator, they carry the catalyst by gas-lift effect and thenecessary pressure differentials for catalyst how are obtained by virtueof the densities in standpipes I0 and 56 being greater than densities ofthe entering gas streams.

The temperature maintained in regenerator 48 may be in approximately thesame range as the temperature maintained in the reactor although inparticular cases the regenerator temperature may be higher or lower thanthe reactor temperature. Thus with the reactor at 400 F. the regeneratormay be operated within the approximate range of 300 to 600 F. or more,preferably 390 to 430" R, e. g. about 415 F. If the hydrogen employedfor catalyst regeneration contains any appreciable amounts of carbonmonoxide the reaction thereof ,with the hydrogen will liberate heat andthus facilitate high temperature operations. Regeneration may beefiected in the presence of appreciable amounts of carbon monoxideprovided that the hydrogen carbon monoxide ratio is much greater thanthat employed in the reactor, 1. c. with ratios in the approximate rangeof 4:1 to 2021 but in this case heat must usually be removed from theregenerator and it may be so removed by any of thenmeans hereinabovedescribed in connection with the reactor. With into absorber 29. Atleast a substantial amount of such gases may be recycled to line 33along with hydrogen entering the base of the regenerator. I prefer,however, to pass the gases from line 5? through cooler 58 in order tocondense normally liquid products, and to introduce the cooled streaminto separator 58 for separating out any condensed materials. Water maybe withdrawn from the settler through line .80 along with-"any catalystparticles that may have been carried over from the regenerator. Liquidhydrocarbons may be withdrawn through line Bi and introduced tofractionator 34. Uncondensed gases which leave the top of the separatorthrough line 62 may then be picked up by compressor 63 for recycle tothe system at any of several points.

Since only a small portion of the hydrogen is usually utilized in aonce-through passage through the regenerator the bulk of the gasesdischarged from compressor 63 may be recycled through line 45 totransfer line 43 so that the hydrogen goes round and round through theregenerator and is thus more completely and eiiectively utilized. Thisrecycling of the hydrogen gas through the regenerator eifects a greatsaving in the amount of relatively pure hydrogen which must beintroduced through line 44 and since the production of hydrogen is moreexpensive than the production of hydrogen-carbon monoxide mixtures, therecycling of regenerator gases through the regenerator eflectssubstantial savings.

That portion of the gas discharged from compressor 63 which is notrecycled to the regeneratormay be passedthrough line 64 to line H forintroduction into the base of reactor l2 and it may thus supply anydeficiency in the hydrogen content of the feed gas. When the hydrogen'by recycling catalyst through a cooler it may be most advantageous toemploy gases discharged by compressor 63 for efiecting catalyst transferAt this temperature level there is usually forma- I through the coolingcircuit. In this case a part .or all of the regeneration gases will bepassed via line through cooler 86. Catalyst from the dense phase in thereactor will pass downwardly through the large internal conduit 61 andstandpipe 68 and may be maintained in aerated condition in the standpipeby means of an inert changer 66, the discharged catalyst preferablyflowing upwardly through tubes in this heat exchanger which tubes aresurrounded with a cooling fluid. The cooled catalyst is then returned tothe reactor' by transfer line 13. A cooling fluid such as water may beintroduced through line 14 around the outside of the tubes and hot wateror steam may be withdrawn through line 15. In this method of operationthe carbon monoxide may be substantially displaced from the catalyst byaeration gas in standpipe 68 and when the hydrogen-rich gas from line 65meets the hot catalyst -in transfer line H and carries it upward to andthrough the cooler it may exert substantial stripping and regenerationof the catalyst, freeing it to a considerable extent of heavy liquid orwaxy deposits. The regeneration thus accomplished is not as effective asthe re-' generation accomplished in regenerator 46 because of the veryshort time "of contact but nevertheless an effective amount 'ofstripping is thus obtained and the catalyst activity is enhanced by itscontact with hydrogen instead of being vdegraded asmight be the case ifsteam were used as the catalyst transfer medium.

Regardless of the particular manner in which the regeneration gases areutilized it will be seen from the 'above' description that I haveprovided,

a methodand means for maintaining substantially constant catalystactivity in the reactor so the top of vessel l2a to a point spaced fromthe bottom thereof. The space between bafiles I6 and 11 forms a conduitwhich serves the function of standpipe 54. A deflector 18 on baffle 'llmay serve to prevent upflowing gases in reaction zone 19 from enteringregeneration zone 80. Deflector 18 may be pivotally mounted so that itsupper end may be moved toward and away from baiile 16 in order tocontrol the rate of flow of fluidized liquid-like catalyst material intoreaction zone 19 and aeration gas may be introduced at this point toexpedite the flow of catalyst into the reaction zone.

The catalyst in the conical base of this chamber is maintained inaerated liquid-like formby aeration gas introduced through line 8|.Hydrogen is introduced through line Ma at such a rate andin such amanner as to provide a gas-- lift eifect in regenerator zone 80. Bymaintaining the dense phase level in zone 80 higher than the dense phaselevelin zone 19 catalyst flow may,

' be maintained in the direction indicated by the arrows and the rate'of catalyst flow may be regulated lay-changing the position of pivotedelement- 18 or by varying the rate at which hydrogen is introducedthrough line 44a.

The reaction product *stream is withdrawn through line 22a; Theregeneration gases are 'w'ithdrawnthrough line 51a, passed through thatthroughout long on-stream periods the prod-.

[uctj yields and the product distribution may be held substantiallyconstant. This uniformity of catalyst activity over a long periodofti'me is accomplished by continuously stripping or regenerating only asmall amount of the catalyst,

the amount passing through the regenerator per day being only about 5 toor preferably 10- to 20%lof the amount of catalyst which is con stantlymaintained in the reactor. The rate at which catalyst is regenerated maythus be controlled and varied over a substantial range so that the totalvolume of catalyst is in effect subjected {to regeneration every 2 to 20days.

Various changes in the specific form of apparatus illustratedinFigure 1may be made without departing from the invention. The standpipes ineither the reactor or-regenerator or both may communicate directly withthe base of the respective chamber and the gases and catalyst materialmay be introduced thereto at a higher level. Structures may be employedas exemplifled byU. S. Letters Patent 2,337,684; 2,341,193, etc. In anyevent, however, catalyst will be maintained in liquid-like denseturbulent suspended phase in both the reactor and the reenerator andthere will be a continuous transfer from the reactor to the regeneratorand from the I 16 extending downwardly from the top of vessel l2a and alower bafilell extending from below cooler 58a-and introduced intosettler 59a from which water is'removed through line 60a and oilthroughline Ma. The gases from the settler are picked up'by compressor63a and the major part of. them returned through line Ma to line Ma andthe rest passed by line 8| for efiecting aeration in the cone-shapedbottom of reactor vessel l2a.

In this case' asin the previous case, regeneration will be effected in aseparate and distinct zone and there will be continuous catalysttransfer from the reactor to the regenerator and thence back to thereactor.

In Figure 3 I have illustrated an embodiment wherein regeneration iseffected in a separate .and distinct internal zone but whereinregeneration gases are combined with the efiluent product.

stream. In this case reactor 12b is provided with a baiile 82 the top ofwhich is below the dense phase leveland the bottom of which ispreferably,

the density in regeneration zone 800 may be sufficientlyless than thedensity of the catalyst in.

reactor [90 so that there will be a net upward flow of catalyst in theregeneration zone 80c as indicated by the arrows. By using sufilcientlylow vertical velocities in regeneration zone 80c the density may begreater than that in reaction zone [90 so that the catalyst flow throughthis zone will be opposite to that shown by the arrows.

In Figure 4 I have illustrated as another embodiment of myzinvention asystem wherein external regenerator 46c communicates with-reactor -l2 cthrough an upper conduit 86 which is'below the dense phase levelinreactor- 12c, and a lower co duit 87 which is "adjacent the bottom ofthe as compared with that in the reactor.

regulating the catalyst density in the regenerator' ploying a low upwardhydrogen velocity in regenerator 480 the catalyst density may besufficiently greater than that in reactor l2c to establish catalyst flowin the direction of the arrows. The remainder of the system in theembodiments illustrated in Figures}; and 4 will be the same ashereinabove described in connection with Figure 1 and hence will requireno .further detailed description. V

Figure 5 has already been described in connec tion with Figure 1 but itshould be pointed out that the aeration gas which is introduced by lineand which aerates the catalyst in the zone between dip leg l6 and pipHlm'ay be hydrogen. By using hydrogen for thus effecting aeration incatalyst transfer I effect a substantial amount of stripping and evenregeneration o the catalyst and since this contacting of thee" talystwith hydrogen is in the substantial, absence of carbon monoxide I caneifect this stripping without undue production of methane. Instead ofmounting pipe l8at an intermediate point in the reactor it maybe mountedat the side thereof and may function in the manner of the embodiment ofmy inventionillustrated by Figure 3, the catalyst in this cas'e beingintroduced into the regeneration zone by cyclone dip leg instead ofbetween baiiles 82 and 83.

In all embodiments of my invention I maintain the regeneration zonesegregated from the reaction zone and effect continuous transfer ofcatalyst from each zone to the other. The regeneration may thus beeifectedin the substantial absence of carbon monoxide which is desirablebecause the presence of carbon monoxide with large I quantities ofhydrogen at temperatures of the order of 400 F. tends to produce undulylarge hydrogen in effecting regeneration is not clearly established butit is definitely more than a simple stripping of volatile products fromcatalyst material. It appears that wax-like deposits accumulate oncatalyst particles and while a certain amount of such deposits may beactually beneficial. these amounts must not become ex- 1 cessive. Withmy continuous regeneration no excessive amounts oi wax-like depositsaccumulate on the catalyst.

While specific embodiments of my invention have been described inconsiderable detail along with operating conditions employed therewithit should be understood that the invention is not limited to theseparticular examples since numerous modifications and alternative methodsof operation will be apparent to those skilled in the art from the abovedescription. Those skilled By emin the art will know for example thatinstead of employing ordinary heat exchangers for cooling the eilluentproduct stream (exchanger 23) and the regenerator gas stream (exchanger58) the presence of carry-over catalyst particles may require the use ofscrubber-coolers, the gas being pass d upwa d y through a liquidscrubber and liquid from the base of the scrubber being pumped through acooler back to the-top'thereof. Such details have been omitted fromapplicants drawings', because it is believed that the invention will' bemore clearly understood from the simplified schematic flowsheets'presented herewith.

It will benoted that the withdrawal of catalyst for continuousregeneration or reactivation may be from the dilute phase as exemplifiedby cyclone separator l8, dip leg l6 and treating zone It (as shown inFigures 1 and 5). The catalyst may be withdrawn directly from the densephase at a point below the upper level thereof, 1. e. to standpipes 40and 68 of Figure. 1, under baflie 11 of Figure 2, between baffles 82 andas ofFigure 3 and through passageway 86 in Figure 4; this embodiment ofthe invention is claimed in my continuation-impart application SerialNumber 731,241, filed February 27, 1947.

I claim:

The method of producing normally liquid products by a carbonmonoxide-hydrogen synthesis reaction which method comprises passing acarbon monoxide-hydrogen mixture upwardly through a reaction zone incontact with a large mass of solid synthesis catalyst regeneratable byhydrogen and of small particle size at such a rate as to produce aliquid-like turbulent dense phase of said catalyst insald zonesuperimposed by a, light catalyst phase, maintaining said zone underconditions of temperature and pressure for effecting reaction of saidcarbon monoxide and hydrogen to produce normally liquid products,centrifugally separating catalyst particles from the upper lightcatalyst phase within the reaction zone itself, passing thecentriiugally separated catalyst as a downwardly moving column into azone which is below the level of the dense catalyst phase and at leastpartially surrounded by said dense catalyst phase in the reaction zonebut which is separated from said dense catalyst phase, introducinghydrogen at a low point in said last-named zone and passing catalystfrom the base of said column back to said dense catalyst phase throughsaid last-named zone while it is simultaneously undergoing aeration withsaid hydrogen.

EVERETT A. JOHNSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,984,380 Odell Dec. 18, 19342,238,726 Feisst et a1. Apr. 15, 1941 2,266,161 Campbell et al. Dec. 16,1941 2,347,682 Gunness May 2, 1944 2,360,787 Murphree et al. Oct. 17,1944

